title: Changes in knee biomechanics after a hip-abductor strengthening protocol for runners with patellofemoral pain syndrome.
abstract: BACKGROUND
  Very few authors have investigated the relationship between hip-abductor muscle strength and frontal-plane knee mechanics during running.
  
  
  OBJECTIVE
  To investigate this relationship using a 3-week hip-abductor muscle-strengthening program to identify changes in strength, pain, and biomechanics in runners with patellofemoral pain syndrome (PFPS).
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  University-based clinical research laboratory.
  
  
  METHODS
  Fifteen individuals (5 men, 10 women) with PFPS and 10 individuals without PFPS (4 men, 6 women) participated.
  
  
  METHODS
  The patients with PFPS completed a 3-week hip-abductor strengthening protocol; control participants did not.
  
  
  METHODS
  The dependent variables of interest were maximal isometric hip-abductor muscle strength, 2-dimensional peak knee genu valgum angle, and stride-to-stride knee-joint variability. All measures were recorded at baseline and 3 weeks later. Between-groups differences were compared using repeated-measures analyses of variance.
  
  
  RESULTS
  At baseline, the PFPS group exhibited reduced strength, no difference in peak genu valgum angle, and increased stride-to-stride knee-joint variability compared with the control group. After the 3-week protocol, the PFPS group demonstrated increased strength, less pain, no change in peak genu valgum angle, and reduced stride-to-stride knee-joint variability compared with baseline.
  
  
  CONCLUSIONS
  A 3-week hip-abductor muscle-strengthening protocol was effective in increasing muscle strength and decreasing pain and stride-to-stride knee-joint variability in individuals with PFPS. However, concomitant changes in peak knee genu valgum angle were not observed.
authors.affiliation: Faculty of Kinesiology, University of Calgary, AB, Canada. rferber@ucalgary.ca
authors.forename: Reed
authors.initials: R
authors.lastname: Ferber
authors.forename: Karen D
authors.initials: KD
authors.lastname: Kendall
authors.forename: Lindsay
authors.initials: L
authors.lastname: Farr
mesh_terms: D000328:Adult; D056352:Athletes; D001696:Biomechanical Phenomena; D005260:Female; D006615:Hip / Q000502:physiology*; D006801:Humans; D007717:Knee / Q000502:physiology*; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000502:physiology; D009132:Muscles / Q000502:physiology; D010147:Pain Measurement; D046788:Patellofemoral Pain Syndrome / Q000628:therapy*; D016059:Range of Motion, Articular / Q000502:physiology; D012046:Rehabilitation; D055070:Resistance Training / Q000379:methods*; D012420:Running